Nuclear ββ decay is a second-order weak process in which an even-even nucleus decays to its neighboring even-even nucleus by turning two neutrons to two protons while emitting two electrons.A nucleus undergoes such ...Nuclear ββ decay is a second-order weak process in which an even-even nucleus decays to its neighboring even-even nucleus by turning two neutrons to two protons while emitting two electrons.A nucleus undergoes such decay by two distinguishable modes,i.e.展开更多
In order to determine the influence of shearer's cutting and neighboring shields' advance on the support resistance variation, leg pressure data of all 235 shields in the panel LW61 of Cumberland coal mine wer...In order to determine the influence of shearer's cutting and neighboring shields' advance on the support resistance variation, leg pressure data of all 235 shields in the panel LW61 of Cumberland coal mine were analyzed. The results show that the relationship between the leg pressure increment and the distance from shield to front drum of shearer is a quadratic function and that the higher leg pressure increment before shield advance tends to be related to adverse roof conditions. In addition, the three proposed leg pressure increment-related parameters and the three traditional parameters(time-weighted average pressure, setting pressure, and final pressure) of approximately 32000 shield supporting cycles were calculated by a self-developed software package to analyze the correlation between them. The results show that there is a powerful connection between them, and that the three proposed leg pressure increment-related parameters could be used as the indexes to evaluate the interaction between shields and the roof, and to identify the periodic weighting.展开更多
Based on the QM/MM optimized X-ray crystal structure of the photosynthetic reaction center (PRC) of purple bacteria Rhodopseudomonas (Rps.) viridis, quantum chemistry density functional method (DFT, B3LYP/6-31G) has b...Based on the QM/MM optimized X-ray crystal structure of the photosynthetic reaction center (PRC) of purple bacteria Rhodopseudomonas (Rps.) viridis, quantum chemistry density functional method (DFT, B3LYP/6-31G) has been performed to study the interactions between the pigment molecules and either the surrounded amino acid residues or water molecules that are either axially coordinated or hydrogen bonded with the pigment molecules, leading to an explanation of the mechanism of the primary electron-transfer (ET) reactions in the PRC. Results show that the axial coordination of amino acid residues greatly raises the ELUMO of pigment molecules and it is important for the possibility of ET to take place. Different hydrogen bonds between amino acid residues, water molecules and pigment molecules decrease the ELUMO of the pigment molecules to different extents. It is crucial for the ET taking place from excited P along L branch and sustains that the ET is a one-step reaction without through accessory bacteriochlorophyll (ABChl b). It is insufficient to treat the whole protein surrounding as a homogeneous dielectric medium.展开更多
We present a semi-analytical model incorporating the effects of edge bond relaxation,the third nearest neighbor interactions,and edge scattering in graphene nanoribbon fi eld-effect transistors(GNRFETs)with armchair-e...We present a semi-analytical model incorporating the effects of edge bond relaxation,the third nearest neighbor interactions,and edge scattering in graphene nanoribbon fi eld-effect transistors(GNRFETs)with armchair-edge GNR(AGNR)channels.Unlike carbon nanotubes(CNTs)which do not have edges,the existence of edges in the AGNRs has a signifi cant effect on the quantum capacitance and ballistic I V characteristics of GNRFETs.For an AGNR with an index of m=3p,the band gap decreases and the ON current increases whereas for an AGNR with an index of m=3p+1,the quantum capacitance increases and the ON current decreases.The effect of edge scattering,which reduces the ON current,is also included in the model.展开更多
The dynamical self-trapping of an excitation propagating on one-dimensional of different sizes with nextnearest neighbor (NNN) interaction is studied by means of an explicit fourth order symplectic integrator. Using l...The dynamical self-trapping of an excitation propagating on one-dimensional of different sizes with nextnearest neighbor (NNN) interaction is studied by means of an explicit fourth order symplectic integrator. Using localized initial conditions, the time-averaged occupation probability of the initial site is investigated which is a function of the degree of nonlinearity and the linear coupling strengths. The self-trapping transition occurs at larger values of the nonlinearity parameter as the NNN coupling strength of the lattice increases for fixed size. Furthermore, given NNN coupling strength, the self-trapping properties for different sizes are considered which are some different from the case with general nearest neighbor (NN) interaction.展开更多
基金supported by the National Natural Science Foundation of China(12141501,12105004,12070131001,11875075,11935003,and 11975031)the National Key R&D Program of China(2017YFE0116700,and 2018YFA0404400)+1 种基金the China Postdoctoral Science Foundation(2020M680183)the High-performance Computing Platform of Peking University,and State Key Laboratory of Nuclear Physics and Technology,Peking University.
文摘Nuclear ββ decay is a second-order weak process in which an even-even nucleus decays to its neighboring even-even nucleus by turning two neutrons to two protons while emitting two electrons.A nucleus undergoes such decay by two distinguishable modes,i.e.
基金provided by the National High Technology Research and Development Program of China(No.2012AA062100)the Program for New Century Excellent Talents in University of China(No.NCET-10-0770)
文摘In order to determine the influence of shearer's cutting and neighboring shields' advance on the support resistance variation, leg pressure data of all 235 shields in the panel LW61 of Cumberland coal mine were analyzed. The results show that the relationship between the leg pressure increment and the distance from shield to front drum of shearer is a quadratic function and that the higher leg pressure increment before shield advance tends to be related to adverse roof conditions. In addition, the three proposed leg pressure increment-related parameters and the three traditional parameters(time-weighted average pressure, setting pressure, and final pressure) of approximately 32000 shield supporting cycles were calculated by a self-developed software package to analyze the correlation between them. The results show that there is a powerful connection between them, and that the three proposed leg pressure increment-related parameters could be used as the indexes to evaluate the interaction between shields and the roof, and to identify the periodic weighting.
基金This work was supported by the National Natural Science Foundation of China(Grant No.39890390) theState Key Basic Research Development Plan(Grant No.G1998010100).
文摘Based on the QM/MM optimized X-ray crystal structure of the photosynthetic reaction center (PRC) of purple bacteria Rhodopseudomonas (Rps.) viridis, quantum chemistry density functional method (DFT, B3LYP/6-31G) has been performed to study the interactions between the pigment molecules and either the surrounded amino acid residues or water molecules that are either axially coordinated or hydrogen bonded with the pigment molecules, leading to an explanation of the mechanism of the primary electron-transfer (ET) reactions in the PRC. Results show that the axial coordination of amino acid residues greatly raises the ELUMO of pigment molecules and it is important for the possibility of ET to take place. Different hydrogen bonds between amino acid residues, water molecules and pigment molecules decrease the ELUMO of the pigment molecules to different extents. It is crucial for the ET taking place from excited P along L branch and sustains that the ET is a one-step reaction without through accessory bacteriochlorophyll (ABChl b). It is insufficient to treat the whole protein surrounding as a homogeneous dielectric medium.
基金This work was supported in part by the Office of Naval Research grant N000140810861in part by NSF grants ECCS-0824157 and CCF-0701547.
文摘We present a semi-analytical model incorporating the effects of edge bond relaxation,the third nearest neighbor interactions,and edge scattering in graphene nanoribbon fi eld-effect transistors(GNRFETs)with armchair-edge GNR(AGNR)channels.Unlike carbon nanotubes(CNTs)which do not have edges,the existence of edges in the AGNRs has a signifi cant effect on the quantum capacitance and ballistic I V characteristics of GNRFETs.For an AGNR with an index of m=3p,the band gap decreases and the ON current increases whereas for an AGNR with an index of m=3p+1,the quantum capacitance increases and the ON current decreases.The effect of edge scattering,which reduces the ON current,is also included in the model.
基金Supported by National Natural Science Foundation of China under Grant No.11271246Natural Science Research Project of Henan Education Department under Grant No.2011B110024+1 种基金Research Fund for Luoyang Normal University under Grant No.qnjj-2009-02for Henan Polytechnic University under Grant No.Q2012-30A
文摘The dynamical self-trapping of an excitation propagating on one-dimensional of different sizes with nextnearest neighbor (NNN) interaction is studied by means of an explicit fourth order symplectic integrator. Using localized initial conditions, the time-averaged occupation probability of the initial site is investigated which is a function of the degree of nonlinearity and the linear coupling strengths. The self-trapping transition occurs at larger values of the nonlinearity parameter as the NNN coupling strength of the lattice increases for fixed size. Furthermore, given NNN coupling strength, the self-trapping properties for different sizes are considered which are some different from the case with general nearest neighbor (NN) interaction.
